Magnetic sensors and magnetoresistive devices have been utilized in a wide variety of applications. However, such devices have, for the most part, utilized conventional semiconductors and are restricted in terms of potential use and development due to inherent limitation of such materials. For instance, non-linear response to an applied magnetic field limits the scalability of such devices and places practical limitations on size reduction. Likewise, magnetoresistance in conventional magnetodiodes is dependent upon transverse magnetic fields. Such a limitation has typically required use of at least two such devices for multi-directional sensing.
As a result, the search for an alternate approach has been an on-going concern in the art. Accordingly, the development of ferromagnetic (III-V) semiconductors has generated much interest in the possibility of new magnetoelectronic devices and all-semiconductor spintronic logic devices. Despite the technological potential of such heterojunctions, little is known about their junction current-voltage characteristics. Even less is known about the magnetoresistance of these heterojunctions. Models have been developed for ideal junction characteristics in a magnetic field, but are based on diffusion of carriers over a potential barrier. Such considerations are, at least in part, due to conventional views of such device structures and current III-V semiconductors; that is, tunneling processes are responsible for forward current characteristics, especially at low temperatures and in heavily doped junctions.